Experimental Investigations based on a Demonstrator Unit to analyze the Combustion Process of a Nitrous Oxide/Ethene Premixed Green Bipropellant

Since the 1960s hydrazine is used as a monopropellant to power rockets, satellites or planetary probes. Due to hydrazine’s high toxicity and the request for safer and cheaper propellants with comparable performance, several so called "Green Propellants" are under investigation. The most prospective candidates seem to be energetic ionic liquids (HAN-based or ADN-based), hydrogen peroxide or nitrous oxide fuel blends. Aside with ADN-based monopropellants the German Aerospace Center's Institute of Space Propulsion in Lampoldshausen is carrying out research on a nitrous oxide/ethene premixed bipropellant. The benefits of this propellant (ISP about 300 s and low toxicity) are facing the challenges like the need for a proper flashback-arrestor and the high combustion temperature (up to 3300 K). The combustion, injection and ignition behavior of the propellant are investigated experimentally using a combustor unit. Calculations with NASA CEA and RPA were performed to derive possible operation points for the combustor as well as for later use in vacuum thrusters. Furthermore the components of the combustor, the test bench as well as results of the first test runs are presented in this paper.